S vs D and Tow/Haul Switch

Yes, you keep the temp down by staying out of OD which results in higher RPMs and a happier truck.

 

I have two questions if you guys can help me out on. So i can have a better understanding.
1. If i have it in S4 and went to a complete stop, ( or slowing down) do i have to switch it back to D, or i can just go to from S4.
2. Can you use the S4 going up or down the hill without any trailer, or is it used for towing only.
TIA

 

I would personally leave in D but as others have stated they use 4s to tow. I use D with tow haul on big hills in the mountains and the truck slows down nicley without loaded or trailer

 

Then again i do have DD exhaust and use the sequential shifting to get her to purrrrr.... so you can use without towing

 

First time towing recently and I was using Tow Haul S5 over the flat prairies and Tow Haul S4 over the rolling hills of Ontario.

No cruise control. RPMs were often under 2k but never above 3k. No issues on highway, taking off at stops or passing vehicles. Km/L or MPG sucked, but I wasn't concerned.

Used D after I unhooked.

 

1. You can leave it in S4. All this does is limit the top gear to 4.
2. You can use it whenever the circumstances warrant. I use mine on steep grades up and down to limit shifting back and forth and for engine braking without a load.

 

Thanks Adam. That’s good to know i dont have to keep switching it. I was at Tahoe and i was switching it back to D each time i stop. Im very grateful for the advise. Thank you again

 

You would feel differently If you seen how hot your transmission fluid was when you were towing ! If you haven't heard 2019+ have no trans cooler and people see upwards of 250 degrees when towing , lucky you can still retro fit your truck with a cooler .

 

I know it doesn't have a cooler but figure it is how they made it, it's new and serviced by dealership.

If anything goes wrong, I'm confident I'll be covered

 

How heavy were you towing? What was your transmission temps ?

 

17' hybrid, 4 people, dog, firewood, supplies, camping gear

Don't have anything to monitor temps, so didn't even think about it or worry about it.

Dry Weight
2,708 lbs.
Payload Capacity
1,138 lbs.
GVWR
3,846 lbs.
Hitch Weight
346 lbs.

 

I have 19 tundra crewmax , tow around 4000lb travel trailer , I keep it in S4 with tow haul ,speed around 60mph, mpg 10 to 12 depends on wind .
Transmission temp around 215 on pan and climbs up between 217 to 220 going up hills . Torque will see up to 245 very rare when stopping and accelerating ( most times goes 235 and drops down).
If I put truck on s5 highway , transmission temp will creep up slowly , S4 is your bet , I take my time and I don't push it more then 60-65 mph which keeps transmission temp under control . RPM is lower then 3 on highway and gets to 3 on hills , plenty of power on S4 and keeps the converter locked also more fluid circulation with higher rpm which is what you want for cooling.